1. Field of the Invention
The present invention relates to a disc unit for such discs as CD and DVD. Particularly, the invention is concerned with a disc unit wherein the insertion and ejection of a disc are performed simultaneously.
2. Description of the Related Art
In a conventional slot-in type disc unit, a conveying roller as a disc conveying means is disposed near the back of an insertion opening and the insertion or ejection of a disc is performed with a feed force of the conveying roller.
For example, there are known a type in which a disc is held between such a conveying roller as mentioned above and a driven roller disposed in parallel with the conveying roller, and a type in which a disc is held between the conveying roller and a disc guide member disposed on, the ceiling surface or the like of the disc unit.
In such conventional disc units, a disc which has been inserted into the disc unit through the insertion opening is conveyed to a disc drive section disposed in an inner portion of the disc unit and is placed on a turntable installed within the disc drive section. Then, the disc conveying means is retracted from the disc and a clamper goes down to hold the disc between it and the turntable. Subsequently, a predetermined rotation is imparted to the disc by means of a spindle motor and thereafter the disc is subjected to reproducing or recording with use of a pickup.
When the disc is to be ejected, the rotation of the spindle motor is stopped and the clamper goes up to release the disc. At the same time, the disc is again held grippingly by the same disc conveying means as that mentioned above. Then, a reverse rotation is imparted to the conveying roller, whereby the disc is ejected from the disc drive section and further from the insertion opening.
However, the conventional disc unit described above involves the following problems.
As the above disc conveying means there is used a tapered conveying roller whose central portion is smaller in sectional area than both end portions of the same roller. The insertion or ejection of a disc is performed while the disc is held between both end portions of the conveying roller. However, the recording surface of the disc is apt to be flawed because the conveying roller comes into abutment against the recording surface perpendicularly to the same surface.
Besides, the conveying roller is usually formed using a synthetic rubber, but the kinetic friction coefficient of rubber is apt to vary depending on ambient temperature and humidity, so it is sometimes impossible to supply an optimum driving force to the disc. In the case where the pressing force against the disc is small, the conveying roller idles and cannot convey the disc.
Further, for the replacement of disc, it is necessary that the disc having been subjected to reproducing or recording be once ejected to the exterior and that a new disc be then inserted into the disc unit. Thus, a considerable time is required for the replacement of disc.